The article "T-Bracing for Stability of Compression Webs in Wood Trusses" (R. Leichti, I. Hofaker, et al., Journal of Structural Engineering, 2002:374-381) presents results of experiments in which critical buckling loads (in kN) for T-braced assemblies were estimated by a finite-element method. The following table presents data in which the factors are the length of the side member and its method of attachment. There were 10 replications for each combination of factors. The data are consistent with the means and standard deviations given in the article.

a. Compute all main effects and interactions.
b. Construct an ANOVA table. You may give ranges for the P-values.
c. Is the additive model plausible? Provide the value of a test statistic and the P-value.
d. Can the effect of attachment method (nail versus adhesive) on the critical buckling load be described by interpreting the main effects of attachment method? If so, interpret the main effects. If not, explain why not.
e. Can the effect of side member length on the critical buckling load be described by interpreting the main effects of side member length? If so, interpret the main effects, using multiple comparisons at the 5% level if necessary. If not, explain why not.

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Attachment Length Critical Buckling Load Adhesive Adhesive Adhesive Nail Nail Nail Quarter Half Full Quarter Half Full 7.90 8.71 7.72 8.88 8.55 6.95 7.07 7.59 7.77 7.86 14.07 13.82 14.77 13.39 198 12.72 9.48 13.59 13.09 12.09 26.80 28.57 24.82 23.51 27.57 25.96 24.28 25.68 21.64 28.16 6.92 5.38 5.38 5.89 6.07 6.37 7.14 6.71 4.36 6.78 9.67 9.17 10.39 10.90 10.06 9.86 10.41 10.24 9.31 11.99 20.63 21.15 24.75 20.76 21.64 2147 25.25 22.52 20.45 20.38